Exhaust Gas Oxygen Sensor Characteristics on Natural Gas Fuel. Topical Report

摘要

An investigation was conducted into the operational characteristics of oxygensensors when using natural gas as the engine fuel. Included is a discussion on oxygen sensor basics, theoretical exhaust concentration levels, the effect of fuel composition, and engine testing which includes an evaluation of new and aged sensors of three different types. Commercially available oxygen sensors were obtained from manufacturers for testing. Sensor output characteristics were measured as a function of equivalence ratio and exhaust gas temperature on an automotive V8 engine. Parameters measured include voltage output level, sensitivity, stability, and range of operation for lean-to-rich fuel-air mixtures. Gaseous exhaust emissions were measured to verify equivalence ratio. Also investigated was sensor durability and subsequent repeatability (signal shift) following 100 hours of sensor aging. A transient response test was conducted on representative sensors to determine if the response to a step change in equivalence ratio was similar to gasoline and compatible with feedback control systems.